1. Field of the Invention
The present invention relates to an on-vehicle display apparatus.
2. Description of the Related Art
In the past, the angle of an optical system (e.g., a concave mirror and a display screen) has been adjustable in a display device, such as a head-up display for a vehicle, for example, such that a display image can be projected on the position according to the position or posture of a driver. A mechanism for the adjustment includes mechanical movable parts, such as gears, and thus may have backlash between gears. For example, in a display device in which automatic change in position of an optical system, such as automatic opening and closing of a display screen, is performed in accordance with ON and OFF of the ignition of a vehicle, the position of the optical system may deviate from a predetermined adjustment position owing to the backlash. Further, the occurrence of such positional deviation causes issues of uncomfortable feeling experienced by the driver and a reduction in convenience. To address such issues, an on-vehicle display apparatus has been known in the past which, in order to reduce a clearance between mechanical movable parts, such as a backlash attributed to a gap between a reflecting mirror and a positioning unit or a rotational movement adjustment device, for example, includes a spring member for biasing the reflecting mirror in one direction (see Japanese Unexamined Patent Application Publication Nos. 2006-143125 and 2001-97073, for example).
Meanwhile, the on-vehicle display apparatus according to the above-described related art requires a special mechanism for reducing the clearance between mechanical movable parts (e.g., a spring member for biasing a reflecting mirror in one direction). Therefore, there arise issues of an increase in the costs required for the configuration of the device and a reduction in the suitability for being mounted on a vehicle and the degree of design layout freedom.